Memory devices and memory subsystems typically have certain initialization steps and/or register values that need to be programmed prior to normal operation. Certain events can cause the initialization to be done improperly including, but not limited to, a reset occurring during the middle of initialization.
If the memory initialization process is interrupted, the memory may wind up in a state in which operation is unpredictable. Memory initialization could be interrupted due to asynchronous resets, such as the user pressing a reset button or reset messages received from the local area network (LAN). The only way to return the memory to a proper state is to power cycle the memory for a sufficiently long time. After reset, there is no direct method for the BIOS to know if the memory is in an unpredictable state. It could infer this by performing extensive memory testing, however that takes a significant time and will slow the boot process.